Problem 13
Question
The crystals of ferrous sulphate on heating give (a) \(\mathrm{FeO}+\mathrm{SO}_{2}+\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{FeO}+\mathrm{SO}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{SO}_{2}+\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}\)
Step-by-Step Solution
Verified Answer
Option (c): \( \text{Fe}_2 \text{O}_3 + \text{SO}_2 + \text{H}_2 \text{SO}_4 + \text{H}_2 \text{O} \).
1Step 1: Determine the Composition
Ferrous sulphate crystals are chemically represented as \( ext{FeSO}_4 imes 7 ext{H}_2 ext{O} \). This means each molecule of ferrous sulphate is associated with seven molecules of water.
2Step 2: Understand the Heating Process
On heating, the water of crystallization in ferrous sulphate is first lost, leading to an anhydrous form. Further heating decomposes anhydrous ferrous sulphate to form iron(III) oxide, sulfur dioxide, and sulfur trioxide.
3Step 3: Chemical Reaction Consideration
The decomposition reaction for ferrous sulphate on heating can be written as: \[ 2 ext{FeSO}_4
ightarrow ext{Fe}_2 ext{O}_3 + ext{SO}_2 + ext{SO}_3 \] This indicates that iron(III) oxide, sulfur dioxide, and sulfur trioxide are formed.
4Step 4: Identify the Correct Option
Compare the chemical decomposition reaction with the given options. Option (c) matches the products resulting from the decomposition: \( ext{Fe}_2 ext{O}_3 \), \( ext{SO}_2 \), \( ext{H}_2 ext{SO}_4 \), and \( ext{H}_2 ext{O} \) (as \( ext{H}_2 ext{SO}_4 \) can condense from \( ext{SO}_3 \)).
Key Concepts
Ferrous Sulphate ChemistryIron(III) Oxide FormationSulfur Dioxide and Trioxide
Ferrous Sulphate Chemistry
Ferrous sulphate, known scientifically as iron(II) sulfate, is an inorganic compound with the formula \( \text{FeSO}_4 \). Often found in the form of heptahydrate, it appears as blue-green crystals commonly referred to as copperas or green vitriol. When ferrous sulphate is hydrated, it is represented as \( \text{FeSO}_4 \cdot 7\text{H}_2\text{O} \). This means each molecule of ferrous sulphate holds seven water molecules in its structure.
Upon heating, the structure undergoes significant changes due to the loss of water of crystallization - the water molecules bound to the salt in its crystalline form. This dehydration is a typical starting reaction in thermal decomposition, and it produces an anhydrous form of ferrous sulphate. The change in the physical and chemical properties of the substance is essential knowledge in understanding how substances behave under different conditions, particularly related to changes in temperature. Depicting these changes through chemical equations is crucial for students to grasp thermal decomposition processes.
Upon heating, the structure undergoes significant changes due to the loss of water of crystallization - the water molecules bound to the salt in its crystalline form. This dehydration is a typical starting reaction in thermal decomposition, and it produces an anhydrous form of ferrous sulphate. The change in the physical and chemical properties of the substance is essential knowledge in understanding how substances behave under different conditions, particularly related to changes in temperature. Depicting these changes through chemical equations is crucial for students to grasp thermal decomposition processes.
Iron(III) Oxide Formation
When heating continues with anhydrous ferrous sulphate, it decomposes further to yield iron(III) oxide, also known chemically as \( \text{Fe}_2\text{O}_3 \). This process is a critical aspect of the compound's thermal decomposition.
Iron(III) oxide is a notable product because it is a stable, rust-colored compound. Understanding its formation is important for students studying chemical reactions involving iron compounds. The balanced chemical equation that represents the decomposition of ferrous sulphate is:
\[ 2 \text{FeSO}_4 \rightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 + \text{SO}_3 \]
This equation shows that for every two molecules of ferrous sulphate that decompose, one molecule of iron(III) oxide is produced. Understanding this stoichiometry helps in predicting the quantities of products formed from a given amount of reactants.
Iron(III) oxide is a notable product because it is a stable, rust-colored compound. Understanding its formation is important for students studying chemical reactions involving iron compounds. The balanced chemical equation that represents the decomposition of ferrous sulphate is:
\[ 2 \text{FeSO}_4 \rightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 + \text{SO}_3 \]
This equation shows that for every two molecules of ferrous sulphate that decompose, one molecule of iron(III) oxide is produced. Understanding this stoichiometry helps in predicting the quantities of products formed from a given amount of reactants.
Sulfur Dioxide and Trioxide
The decomposition of ferrous sulphate also yields sulfur dioxide (\( \text{SO}_2 \)) and sulfur trioxide (\( \text{SO}_3 \)), two significant gaseous byproducts. These gases are of environmental and industrial relevance.
\( \text{SO}_2 \) is a colorless, toxic gas with a pungent odor, commonly associated with the smell of burning sulfur. It is crucial in industries for producing sulfuric acid, which involves converting \( \text{SO}_2 \) to \( \text{SO}_3 \).
\( \text{SO}_3 \) can combine with water vapor, condensing to form sulfuric acid (\( \text{H}_2\text{SO}_4 \)), a vital substance in chemical manufacturing. The reaction can be simplified to show:
\[ \text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4 \]
This formation of sulfuric acid from sulfur trioxide highlights its significance and underlines the importance of understanding these decomposition reactions. Controlling and predicting these reactions is a cornerstone of industrial processes and environmental management.
\( \text{SO}_2 \) is a colorless, toxic gas with a pungent odor, commonly associated with the smell of burning sulfur. It is crucial in industries for producing sulfuric acid, which involves converting \( \text{SO}_2 \) to \( \text{SO}_3 \).
\( \text{SO}_3 \) can combine with water vapor, condensing to form sulfuric acid (\( \text{H}_2\text{SO}_4 \)), a vital substance in chemical manufacturing. The reaction can be simplified to show:
\[ \text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4 \]
This formation of sulfuric acid from sulfur trioxide highlights its significance and underlines the importance of understanding these decomposition reactions. Controlling and predicting these reactions is a cornerstone of industrial processes and environmental management.
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